Four-in-one pen



FIG. 1 is a front elevational view of a four-in-one pen showing my new design;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a left side elevational view thereof;

FIG. 6 is a right side elevational view thereof;

FIG. 7 is a front top perspective view thereof;

FIG. 8 is a rear bottom perspective view thereof; and,

FIG. 9 is a front top perspective view thereof in an exploded condition. 

The ornamental design for a four-in-one pen, as shown and described. 